Hiya,
It mainly depends on hwo much your partner/husband earns, if you have one. Unless he is extremely well/poorly paid, it's unlikely to effect them - it didn't for us anyway (I could be wrong on the figures, but I think I was told that it's between about £23k and £70k ish that it makes no difference).
I can understand you not wanting to work f/t, I certainly didn't and am still searching for a p/t job to suit me and my LO! I'd rather not work at all and sacrifice all luxuries than go back and miss all of the 'firsts', they're only young once!
HTH, if you're unsure you could ring them, I found them really helpful on the phone,
Corinna x